Our objectives is to develop a more effective approach to photodynamic therapy (PDT) of cancer by combining two emergent technologies: a) New photosensitizers with improved photochemical characteristics which operate in the deep red wavelength region where body tissue is most translucent, and b) The alexandrite laser1, a superior wavelength tunable solid state laser source in this spectral region. Included among these new photosensitizers are verdins2, purpurins3, bacteriochlorin4, silicon naphthalocyanine5,6,7 and bacteriopheophorbide8, with peak absorption, respectively, at xxxx, 715nm, 765nm, and 755nm. While an emergent technology, laboratory alexandrite lasers, continuously tunable from 710nm to over 800nm in pulsed mode and 740nm to 800nm is continuous mode, have demonstrated performance will within application requirements, and are well adapted to fiber optic delivery. The objectives of this first phase are the construction of a suitably configured alexandrite laser for PDT experimentation, and the test and evaluation of this laser with the verdins and other appropriate photosensitizers using laboratory rats by established methods. The results will guide further development of the laser, beam delivery apparatus and treatment protocol, leading, potentially, to a cost effective clinical laser for PDT.